SaTScan is a free software product for geographical cluster detection and inference. It is used to evaluate whether observations such as disease incidence or mortality are randomly distributed over space and/or time, or whether there are statistically significant spatial and/or temporal clusters with more (or fewer) cases than expected. It has become widely used for chronic diseases, such as evaluating whether a cancer cluster is likely to be due to chance or not, as well as for infectious diseases, such as the daily monitoring of emergency room data for the early detection of disease outbreaks. As the number of users increase, with different types of data and different types of questions to be answered, there is an unmet need for new SaTScan features and functionalities, including the development new variations of the underlying statistical methods for different types of data, a wider variety of input and output options, enhancements to increase user-friendliness, increased speed for large data sets, versions for alternative operating systems, and broader and more detailed documentation. In this project, we propose to further develop and maintain the SaTScan software to fulfill many of these needs.